The present invention relates to a serial data bus with a two-wire line and with a plurality of bus nodes for the exchange of data messages in both directions between the bus nodes and a central unit connected to the serial data bus and for the current supply of the bus nodes, wherein conflicts between data messages that appear simultaneously are resolved on the basis of the priority thereof.
Serial data buses of this type are known in many versions. One of the problems to be solved with such buses consists in guaranteeing a reaction-time to node data that is as short as possible, this being achieved as a rule by a correspondingly high bit rate. However, since each increase in the bit rate results in an increase in the costs of the bus system, this solution cannot generally be adopted. When such a bus is designed with a plurality of nodes, the transport of relatively high currents on the bus may be required in order to be able to connect as many nodes as possible to the central unit. However, it has not hitherto been possible to achieve this requirement satisfactorily, so that until now two-wire buses have only been used in systems with a limited number of nodes or with nodes that consume only very little current.
Therefore, an object of the present invention is to provide a serial data bus that is distinguished by a low bus node cost (and hence low costs for the entire bus), and which in addition will accommodate relatively high currents.